I'm trying to trace your SDA and SCL wires from the Raspberry Pi to the SunControl board. Do you have pull-ups on SDA and SCL? Make sure that SDA goes to SDA and SCL goes to SCL. If you are SURE that this is true, then you have a bad board for some reason.
Now, before you do that, connect your I2C temperature and humidity sensor to the jumpers that you have plugged into the SunControl board to eliminate bad wiring or bad wires.